A Multispectral Polarized Scene Projector (MPSP) had been developed in the short-wave infrared (SWIR) regime for the test & evaluation (T&E) of spectro-polarimetric imaging sensors. This MPSP generates multispectral and hyperspectral video images (up to 200 Hz) with 512×512 spatial resolution with active spatial, spectral, and polarization modulation with controlled bandwidth. It projects input SWIR radiant intensity scenes from stored memory with user selectable wavelength and bandwidth, as well as polarization states (six different states) controllable on a pixel level. The spectral contents are implemented by a tunable filter with variable bandpass built based on liquid crystal (LC) material, together with one passive visible and one passive SWIR cholesteric liquid crystal (CLC) notch filters, and one switchable CLC notch filter. The core of the MPSP hardware is the liquid-crystal-on-silicon (LCoS) spatial light modulators (SLMs) for intensity control and polarization modulation.
This newly developed prototype Multispectral Polarized Scene Projector (MPSP), configured for the short wave
infrared (SWIR) regime, can be used for the test & evaluation (T&E) of spectro-polarimetric imaging sensors. The
MPSP system generates both static and video images (up to 200 Hz) with 512×512 spatial resolution with active spatial,
spectral, and polarization modulation with controlled bandwidth. It projects input SWIR radiant intensity scenes from
stored memory with user selectable wavelength (850-1650 nm) and bandwidth (12-100 nm), as well as polarization
states (six different states) controllable on a pixel by pixel basis. The system consists of one spectrally tunable liquid
crystal filter with variable bandpass, and multiple liquid crystal on silicon (LCoS) spatial light modulators (SLMs) for
intensity control and polarization modulation. In addition to the spectro-polarimetric sensor test, the instrument also
simulates polarized multispectral images of military scenes/targets for hardware-in-the loop (HIL) testing.
A newly fabricated Infrared Scene Projector (IRSP) configured for the Long Wave IR (LWIR) regime has
demonstrated simulated apparent temperatures exceeding 1500 oC, more than doubling the maximum
temperature capability of prior pixilated scene projector devices. Since the entire array surface is capable of
this high temperature output, the same device can be used to generate both the moderate temperature scene
background and an unlimited number of high temperature targets in the scene, without having to optically
combine a few discrete "hot spot" generators. This performance was enabled by advances in a new large pixel,
high voltage, 16-bit backplane Spatial Light Modulator (SLM) coupled with an intense spectral illumination
source, and special formulation liquid crystal (LC). The new LC formulation and SLM configuration also
achieves an effective usable frame rate of up to 200Hz capability. Performance characterization and resulting
data will be discussed in the paper.
A Liquid Crystal on Silicon (LCoS) Spatial Light Modulator device was fabricated into an IR Scene Projector Concept Demonstrator for MWIR Hardware-in-the-loop Testing. Presently on-going in-house efforts are establishing performance benchmarks that rival many of the capabilities of the alternative, and presently the high end performance standard device, the suspended-bridge resistor array. New adaptations, like incorporating Ferro-electric Liquid Crystal (FELC) can achieve improved IR performance values breaking through the "slow" settling time limit exhibited by earlier Liquid Crystal based systems. In fact, specific parameters may even exceed some of the resistor array parameter's performance values (such as apparent thermal rise time allowing an overall faster frame rate). In addition, the relatively simple CMOS fabrication for the basic chip and ease of system "customization" allows system fabrication cost to be more on the order of the economical low end performance Digital Mirror Devices for the Infrared waveband; but still keeps the analog controlled thermal gradient in a single switch time to accommodate fast integrating sensors of modern seeker systems. Our research is using a 512x512 array originally intended for visible applications, but tailored for the MWIR operational regime. A new CMOS fabrication run to incorporate additional features and achieve further performance benefits is planned, but the existing product capability is adequate for most HIL simulation requirements. The measured performance of our in-house prototype device using FELC will be discussed.
Computer Science and Applications has implemented a fast, automated non-uniformity correction procedure for a 512 X 512 infrared projection array that takes advantage of a relatively inexpensive 256 X 256 infrared camera. The procedure is based on the sparse matrix approach defined in `A simplified method for the hardware implementation of nonuniformity correction on a resistor array infrared scene projector.'
The KHILS Vacuum Cold Chamber (KVACC) provides the capability of testing IR seekers with scenes involving a `cold' background, more closely simulating a high altitude/exoatmospheric engagement. During the past year, a gaseous helium refrigeration system has been installed to simplify the logistics of cooling the chamber. An antechamber has also been installed to serve as a chamber for the sensor under test. A WISP array was installed in the Source Chamber. A thermal control system was developed by connecting the array to a cold surface by way of a thermal choke, then actively controlling the temperature with heating elements. This made it possible to operate the array at user selected, stable substrate temperatures ranging from ambient temperature to below 150 K. This capability makes it possible to select the infrared background level that the array operates at, and to operate with background levels that are adequate for testing the high altitude/exoatmospheric engagements. WISP arrays were designed for room temperature operation, but predicted performance at reduced temperatures appears acceptable. Tests were performed with a Phase I prototype WISP array inside the KVACC Source Chamber. Data on this array's radiometric response at various substrate temperatures are presented. It is demonstrated that the arrays can be operated at substrate temperatures as low as 145 K. Currently two Phase 3 WISP arrays and a dichroic beam combiner are being installed in the Source Chamber for 2- color testing.
The KVACC is a part of the Air Force Kinetic-kill vehicle Hardware-In-the-Loop Simulator facility whose purpose is to enable IR scene projection with a below ambient `cold' background for increased dynamic range and closer simulation realism. The geometric and spectral description of the system will be presented in the paper along with discussion as to operational details including cleanliness requirements, vacuum pump down time, and chill down rates using LN2. In addition, the lessons learned from integration checkout using a 512 X 512 Cryogenic Resistor array Infrared Scene Projector will be annotated. Upgrade potential and future plans, including Helium refrigerators will also be detailed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.